1. Field of the Invention
The present invention relates to a display device, and more particularly, to an organic electro-luminescence display (OELD) and a fabricating method thereof.
2. Discussion of the Related Art
Until recently, display devices generally have employed cathode-ray tubes (CRTs). Presently, much effort has seen made to study and develop various types of flat panel displays, such as liquid crystal display devices (LCDs), plasma display panels (PDPs), field emission displays, and organic electro-luminescence displays (OELDs), as substitutes for CRTs. Among these flat panel displays, the PDP has a large display size but low lightness and high power consumption. The LCD has thin profile and low power consumption, but a small display size. The OELD is a luminescent display that has fast response time, high lightness and wide viewing angle.
FIG. 1 is a view of an equivalent circuit for an OELD according to the related art. As shown in FIG. 1, the OELD includes a data line DL and a gate line GL crossing each other to define a pixel region P, and a power line VDDL. In the pixel region P, a switching transistor TS, a driving transistor TD, a storage capacitor CST and an organic emitting diode E are arranged. The switching transistor TS turns on or off by a gate signal applied through the gate line GL. When the switching transistor TS turns on, a data signal is applied to the driving transistor TD through the data line DL. The driving transistor TD turns on or off by the applied data signal. When the driving transistor TD turns on, a power signal is applied to the organic emitting diode E through the power line VDDL so that the organic emitting diode E emits light.
FIG. 2 is a cross-sectional view of an OELD according to the related art. As shown in FIG. 2, the OELD includes a first substrate 70 as a lower substrate, and a second substrate 90 as an encapsulation substrate facing the first substrate 70. Also, on the first substrate 70, an array layer AL and an organic emitting diode E on the array layer AL are disposed. The array layer Al includes a transistor T. The organic emitting diode E includes a first electrode 72, an organic emitting layer 74, and a second electrode 76. Since the first electrode 72 is made of a transparent material, light emitted from the organic emitting layer 74 goes toward the first substrate 70. On the other hand, the second substrate 90 has a sunken portion 92 filled with a desiccant 94. The desiccant 94 blocks outer moisture so as to protect the organic emitting diode E.
The OELD of FIG. 2 is regarded as a bottom emission type OELD because of its light emission direction. In this bottom emission type OELD, since the array layer AL and the organic emitting diode E are both formed on the lower substrate 70 as light-emitting elements, if either one has a problem, the lower substrate 70 is considered as a defective substrate, thereby reducing the production efficiency of the OELD. Moreover, in the bottom emission type OELD, since elements such as the transistor and metal lines blocks light emission from the bottom, the aperture ratio of the OELD is small, thereby causing difficulty to achieve high resolution.